Light emitting diode driving device

Abstract

A LED driving device is electrically connected to a voltage power source and a plurality of LED strings. The LED driving device includes a constant-voltage outputting module, a rectifying unit, and a constant-current controlling unit. The constant-voltage outputting module is electrically connected to the voltage power source and includes a switching unit, a resonant unit, a converting unit, and a power-balancing unit. The resonant unit is electrically connected to the switching unit. The converting unit includes a primary winding, two first secondary windings, and a second secondary winding. The primary winding is electrically connected to the resonant unit. The power-balancing unit includes a balancing converter including two balancing windings electrically connected to the first secondary windings. The rectifying unit is electrically connected to the power-balancing unit and the LED strings, the constant-current controlling unit is electrically connected to the second secondary winding and the LED strings.

What is claimed is: 
     
         1 . A light emitting diode (LED) driving device electrically connected to the voltage power source and a plurality of LED strings, the LED driving device comprising:
 a constant-voltage outputting module electrically connected to the voltage power source, the constant-voltage outputting module comprising:   a switching unit;   a resonant unit electrically connected to the switching unit;   a converting unit comprising a primary winding, two first secondary windings, and a second secondary winding, the primary winding electrically connected to the resonant unit; and   a power-balancing unit comprising a balancing converter, the balancing converter comprising two balancing windings electrically connected to the first secondary windings;   a rectifying unit electrically connected to the power-balancing unit and the LED strings; and   a constant-current controlling unit electrically connected to the second secondary winding and the LED strings.   
     
     
         2 . The LED driving device in  claim 1 , wherein the constant-current controlling unit comprises a driving component and a power-converting circuit, the constant-current controlling unit is electrically connected to the LED strings, and the power-converting circuit is electrically connected to the driving component and the second secondary winding. 
     
     
         3 . The LED driving device in  claim 2 , wherein the power-balancing unit further comprises two balancing capacitors electrically connected to the first secondary windings and the rectifying unit, each balancing capacitor, each first secondary winding, and each balancing winding are electrically connected in in series. 
     
     
         4 . The LED driving device in  claim 3 , further comprising a controller electrically connected to the second secondary winding and the switching unit, the controller is configured to control switching frequencies of the switching unit. 
     
     
         5 . The LED driving device in  claim 4 , further comprising a plurality of protecting capacitors, each protecting capacitor is electrically connected to each LED string in parallel. 
     
     
         6 . The LED driving device in  claim 5 , wherein the rectifying unit comprises two first rectifiers and two second rectifier, the first rectifiers are electrically connected to the first secondary windings and the LED strings, respectively, the second rectifier is electrically connected to the second secondary winding. 
     
     
         7 . The LED driving device in  claim 6 , further comprising a voltage-level sensing capacitor electrically connected to the second rectifier. 
     
     
         8 . The LED driving device in  claim 7 , wherein the balancing windings comprise the same turn number. 
     
     
         9 . The LED driving device in  claim 8 , wherein the resonant unit comprising a resonant capacitor, a resonant inductor, and a magnetizing inductor, the resonant capacitor, the resonant inductor, and the magnetizing inductor are electrically connected in series, the magnetizing inductor is electrically connected to the primary winding in parallel. 
     
     
         10 . The LED driving device in  claim 9 , wherein the switching unit comprises two switching components electrically connected to the controller, the controller is configured to modulate switching frequencies of the switching components.